Re: [lwip-users] chaining pbufs as an user

[mgroups]

Hello Simon,

can you please check the code please, if it is correct or a bug.
Thanks a lot for your help!
http://cvs.savannah.gnu.org/viewvc/contrib/apps/tcpecho_raw/echo.c?revision=1.3&root=lwip&view=markup

On Thu, 22 Jul 2010 08:22:29 +0200, Simon Goldschmidt wrote:

Mike Kleshov wrote:

Again, if I am not mistaken, the while loop is needed if there is more
than 1 reference to the pbuf in question. Perhaps, in this particular
program this will never happen. Maybe the author of the code put the
while loop there just to be on the safe side?

I didn't have a look at the code yet, bug writing such a loop is not a good idea at all: you should only call pbuf_free as often as you called pbuf_ref (and once more for the original reference passed to you, of course). Calling pbuf_ref as long as the pbuf has actually been freed would mean that if anyone else actually had a reference stored to that pbuf, it would get deallocated without the other one noticing. That sounds like a bug in that example code to me!

Simon

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